Exemplary embodiments of the invention relate to an engine block arrangement having an exhaust gas system.
Engine block arrangements are already known in which components of the exhaust gas system are situated near an engine block. An article in Motortechnische Zeitschrift (MTZ), 10, 2011, pages 762-768 describes an engine block arrangement having an exhaust gas system of a diesel engine that includes an oxidation catalytic converter and a particle filter. Both elements are jointly situated in a housing on one side of the engine block. This has the advantage that these elements reach their operating temperature very quickly, and that heat losses from the exhaust gas, which occur over a fairly long distance from the engine to the components, may be kept low. The known exhaust gas system has only two components having exhaust emission control activity situated near the engine. In more complex exhaust gas systems, in particular those having an additional catalytic converter for a selective catalytic reaction (SCR catalytic converter), placement near the engine is typically not possible due to installation space reasons. An SCR catalytic converter is used to reduce nitrogen oxides (NOx), in particular in the exhaust gas of diesel internal combustion engines. For this purpose, a urea-water solution is introduced into the exhaust gas flow in the area of a mixing section, the mixing section being used to thoroughly mix the urea-water solution with the exhaust gas and as a reaction section, along which the urea reacts with the water to form ammonia and carbon dioxide. The ammonia in turn reacts in the SCR catalytic converter with the nitrogen oxides of the exhaust gas flow, thus lowering the nitrogen oxides concentration. The mixing section must have a certain length to ensure its functioning. For this reason, the SCR catalytic converter is typically situated in a vehicle underbody area in order to provide a sufficiently long path for the exhaust gas flow from the engine block to the SCR catalytic converter. This has the disadvantage that temperature and pressure losses occur in the exhaust gas flow. In addition, a sensor system for adding the urea-water solution as well as for the SCR catalytic converter must be laboriously mounted and connected to the vehicle electronics system. Furthermore, the arrangement of the components in the vehicle underbody area depends on the vehicle type, so that a large number of exhaust gas system variants is necessary, which entails logistical problems and high costs.
European patent document EP 2 123 878 A1 discloses a compact arrangement of a particle filter and an SCR catalytic converter in which the particle filter is connected to the SCR catalytic converter via a pipe extending essentially in an S shape. This allows a compact arrangement of the components next to one another, and at the same time, a sufficiently long mixing section between same. However, this compact arrangement per se is still provided in the vehicle underbody area, resulting in the corresponding disadvantages.
Exemplary embodiments of the present invention are directed to an engine block arrangement having an exhaust gas system that does not have the mentioned disadvantages. In particular, the aim is to avoid temperature and pressure losses in the exhaust gas flow to the greatest extent possible, to simplify connection and mounting of a sensor system in particular in the area of the SCR catalytic converter, and to implement the arrangement regardless of the vehicle type, thus greatly reducing the number of variants that must be kept on hand.
The exhaust gas system, viewed in the flow direction of an exhaust gas flow, includes the following components arranged one behind the other: an exhaust gas turbocharger, an oxidation catalytic converter, a feed device for urea-water solution, a particle filter, and an SCR catalytic converter. The engine is designed as an internal combustion engine, preferably as a diesel engine. The engine block arrangement is characterized in that the exhaust gas turbocharger, the oxidation catalytic converter, the feed device for urea-water solution, the particle filter, and the SCR catalytic converter are situated together on the engine block along one side thereof. The side on which the components of the exhaust gas system are situated is oriented essentially perpendicularly with respect to an output side of the engine block. The term “output side” refers to the side of the engine block at which a transmission is situated. If the internal combustion engine is designed as a diesel engine, the oxidation catalytic converter is preferably designed as a diesel oxidation catalytic converter. Correspondingly, the particle filter is preferably designed as a diesel particle filter. Due to the components of the exhaust gas system being jointly situated on the same side of the engine block, these components are situated very close to one another and near the engine, so that they are heated by the waste heat of the engine, i.e., they quickly reach and maintain their operating temperature. In addition, due to the resulting small line lengths, temperature and pressure losses in the exhaust gas flow are largely avoided. The arrangement is independent of the specific vehicle type, since the exhaust gas system together with the engine block is designed as a module, in a manner of speaking. The exhaust gas system together with the engine block may thus be accommodated in an engine compartment of the vehicle. None of the mentioned components of the exhaust gas system is accommodated in the area of a vehicle underbody. Due to all components being jointly situated on one side of the engine block, mounting and connection of the sensor system for the exhaust gas system is also greatly simplified.
The engine block arrangement can also include the particle filter and the SCR catalytic converter being situated together in a container. The container is also referred to as a “combi-box,” and is typically designed as a sheet steel housing having an inlet funnel for supplying exhaust gas into the housing, and an outlet funnel for discharging cleaned exhaust gas from the housing. Due to the closely adjoining arrangement in a shared housing, in particular temperature and pressure losses between the particle filter and the SCR catalytic converter are largely avoided.
In addition, an engine block arrangement can include the particle filter having inlet channels and outlet channels, and walls of the inlet channels with a coating for a selective catalytic reaction, i.e., an SCR catalyst coating. Walls of the outlet channels preferably also have an SCR catalyst coating. As a result, the particle filter may already have a selective catalytic action with regard to nitrogen oxides reduction. This reduction in NOx in addition to the NOx reduction by the downstream SCR catalytic converter allows particularly low NOx emission values.
The engine block arrangement can have the components of the exhaust gas system situated relative to one another in such a way that the exhaust gas flow from an outlet from the exhaust gas turbocharger to an outlet from the SCR catalytic converter undergoes at least one deflection of the main exhaust gas flow direction by approximately 180°. If exactly one deflection by approximately 180° is provided, the length of the engine block is preferably utilized twice for situating the components of the exhaust gas system at the engine block. If two deflections by approximately 180° are provided, this length is correspondingly utilized three times. Similarly, it is also possible to provide more than two deflections by 180°. The number of deflections makes it possible to coordinate the arrangement of the components of the exhaust gas system, i.e., the exhaust gas turbocharger, the oxidation catalytic converter, the feed device for the urea-water solution, the particle filter, and the SCR catalytic converter, on a specific engine block, and in particular to coordinate with the length of the engine block. Thus, for an engine block having a fairly large overall length it is sufficient to provide only one deflection by approximately 180°. If a smaller overall length is available, for example two or also more than two deflections by approximately 180° may be provided.
The engine block arrangement can also have the exhaust gas turbocharger and oxidation catalytic converter connected to one another by a pipe extending essentially in the longitudinal direction of the engine block. A “longitudinal direction” refers to the direction of the engine block which extends from the output side of the engine block to a side facing away from same. The side facing away from the output side of the engine block is also referred to as a vibration damper side due to the fact that a vibration damper is preferably provided here. When the term “vibration damper side” is used below, this is not to be construed in a limiting manner such that a vibration damper must necessarily be provided on this side. Instead, the term is used for short for the side facing away from the output side of the engine block. In the engine block arrangement, a flow length for the exhaust gas from an exhaust gas turbocharger outlet to an oxidation catalytic converter inlet is less than 300 mm, preferably 200 mm.
The engine block arrangement can also include the oxidation catalytic converter and the particle filter being connected to one another by a pipe and situated relative to one another in such a way that the exhaust gas flow from an oxidation catalytic converter outlet to a particle filter inlet undergoes a deflection of essentially 90°. This is provided when a relatively large overall length is available for the components of the exhaust gas system. This is the case when the engine block is installed in a vehicle in the longitudinal direction. If a smaller overall length is available, which may be the case in particular when the engine block is installed crosswise, it is preferably provided that the exhaust gas flow from an oxidation catalytic converter outlet to a particle filter inlet undergoes two deflections by essentially 180°. The exhaust gas flow is then deflected once by 180° after it exits from the oxidation catalytic converter, is preferably returned for a certain distance, and lastly is deflected a second time by 180°, so that it enters the particle filter essentially in the same direction in which it has also entered the oxidation catalytic converter.
The engine block arrangement can also have the pipe, which is between the oxidation catalytic converter and the particle filter, include a mixing section along which the feed device for urea-water solution and preferably a static mixer in particular are situated. The mixer is used for thorough intermixing of the urea-water solution with the exhaust gas flow. The pipe between the oxidation catalytic converter and the particle filter is preferably designed to be long enough to allow at least essentially complete thermolysis and/or hydrolysis of the urea introduced into the exhaust gas.
The engine block arrangement can have the exhaust gas turbocharger situated substantially, preferably completely, above an exhaust manifold. This results in additional installation space for the arrangement of the exhaust gas system at the engine block.
The engine block arrangement can have the oxidation catalytic converter situated substantially above the exhaust manifold. In particular, when the oxidation catalytic converter is situated approximately at the level of the exhaust gas turbocharger, a connection between these elements may be kept as short as possible.
The engine block arrangement can also have the particle filter and the SCR catalytic converter situated substantially below the exhaust manifold and substantially, preferably completely, above an engine mounting, and preferably approximately centrally relative to the exhaust gas turbocharger. In the preferred embodiment, the exhaust gas turbocharger in a top view is thus situated approximately centrally with respect to the preferably closely adjoining components, namely, the particle filter and SCR catalytic converter, situated in a shared housing.
In this way, optimal use is made of an installation space at the side of the engine block, and the components do not collide with the engine mounting.
The engine block arrangement can also include the exhaust gas turbocharger being situated closer to the output side of the engine block than to the vibration damper side of the engine block, the oxidation catalytic converter being situated closer to the vibration damper side than to the output side. In particular when only one deflection of the exhaust gas flow by 180° is provided, this ensures particularly space-saving and favorable guiding of the exhaust gas flow, and thus, the arrangement of the components of the exhaust gas system. In particular when the engine block is installed lengthwise, viewed in the vehicle direction, in this case an outlet from the SCR catalytic converter is oriented toward the vehicle rear end. In that case, it is not necessary to provide additional deflection of the exhaust gas flow downstream from the SCR catalytic converter.
The engine block arrangement can also have the exhaust gas turbocharger and the oxidation catalytic converter situated relative to one another in such a way that the exhaust gas flow from an exhaust gas turbocharger outlet to an oxidation catalytic converter inlet undergoes a deflection of essentially 90°. The exhaust gas turbocharger is preferably aligned in the longitudinal direction of the engine block, i.e., essentially horizontally. The exhaust gas then preferably flows through the oxidation catalytic converter in a direction that is oriented essentially perpendicularly with respect to the longitudinal direction of the engine block, and preferably oriented toward a bottom side of the engine block. The exhaust gas flow through the oxidation catalytic converter preferably also takes place from top to bottom, viewed relative to the vehicle in which the engine block is installed.
The engine block arrangement can also include the exhaust gas turbocharger being situated closer to the vibration damper side of the engine block than to the output side of the engine block. The oxidation catalytic converter is then situated closer to the output side than to the vibration damper side. This arrangement is preferred when a fairly small overall length is available, so that two deflections of the exhaust gas flow by 180° may be necessary. This may be the case when the engine block is installed crosswise, viewed in the direction of the vehicle. However, it is also possible to implement the described arrangement for a lengthwise installation, in particular when little installation space is available. In this case, due to the two deflections of the exhaust gas flow by 180°, in this arrangement as well the exhaust gas exits the SCR catalytic converter toward the vehicle rear end, so that no further deflection is necessary.
The engine block arrangement can include the oxidation catalytic converter being situated relative to the mixing section, and the mixing section being situated relative to the particle filter, in such a way that the exhaust gas flow from an oxidation catalytic converter outlet to an inlet into the mixing section undergoes a deflection of essentially 180°, and from an outlet from the mixing section to an inlet into the particle filter undergoes a deflection of essentially 180°. Thus, two deflections of the exhaust gas flow by 180° are provided, an S-shaped connection, in a manner of speaking, of the oxidation catalytic converter to the particle filter being provided which includes the mixing section. The mixing section is therefore situated between the oxidation catalytic converter and the particle filter in such a way that the exhaust gas flows back, in a manner of speaking, through the mixing section, viewed in the longitudinal direction, whereby the flow through the oxidation catalytic converter and through the particle filter takes place in the same direction, while the flow through the mixing section takes place in the opposite direction. As stated above, such an arrangement of the components of the exhaust gas system is suited for installation situations having limited installation space or limited overall length. This may typically be the case when the engine block is installed crosswise, viewed in the vehicle direction.
Lastly, the engine block arrangement can have the particle filter and the SCR catalytic converter situated substantially below the exhaust gas turbocharger and also substantially below the oxidation catalytic converter. This means a particularly compact arrangement of the components, which logically are situated close to one another in order to minimize temperature and pressure losses. The components are preferably situated next to one another in pairs, namely, the exhaust gas turbocharger and the oxidation catalytic converter on the one hand and the particle filter and the SCR catalytic converter on the other hand.